Ireland will be without Paddy Jackson for their summer tour to Argentina after the fly-half aggravated a back injury.

The Ulster fly-half has a stress fracture in his lower back, a problem that has been niggling him all season. It is understood he did not train with the national team during a two-day training camp ahead of the trip to South America and, on returning to Ulster, was advised to withdraw from the tour.

Jackson had been named along with Jonny Sexton as one of two No.10s in Joe Schmidt's squad for the two-Test series and will now be replaced in the touring party by Leinster's Ian Madigan.

Jackson struggled with injury during Ulster's defeat by Leinster last Saturday and was forced off in the second half. The Irish Rugby Football Union confirmed that he will be rested this summer in a bid to be fit for next season.